The present invention relates to an orthosis for fastening to a human hand for immobilizing the carpometacarpal joint and metacarpophalangeal joint of the thumb of the hand.
Orthoses of this type are used in order to immobilize and fix the carpometacarpal joint and/or metacarpophalangeal joint of a user within the scope of treatment for chronic, posttraumatic or postoperative states of sensitivity or other pathological states in the region of said joints and to secure said joints in a defined position. One example of a pathological state in which such an orthosis can advantageously be used is what is referred to as rhizarthrosis of the thumb, i.e. arthrosis or degenerative chondrolysis in the region of the carpometacarpal joint. A further example is what is referred to as ski thumb in which, following the thumb being bent away outward in the metacarpophalangeal joint, for example in the event of a fall, an ulnar collateral ligament tear of the thumb has occurred.
It is desirable here for the functionality of the user's hand to be restricted as far as possible only insofar as is required for immobilizing or fixing the affected joints. In particular, it is desirable to put the user in the position of still being able to carry out a pinch grip by the thumb being secured in a position opposite the index finger, and the index finger being able to be brought into contact with the thumb in the manner of pincers in order to grasp objects.
Known orthoses are generally configured in such a manner that, when used correctly, said orthoses are adjacent to the wrist or end at the latter and therefore interfere with movements in the wrist and cause pressure points. Furthermore, they are generally configured in such a manner that they engage around the metacarpophalangeal joint of the thumb and provide an extensive covering of the thumb as far as the distal phalanx. One example is the orthosis which is disclosed in DE 20 2009 017 438 U1 and has a tubular main section and a thumb section. The main section is configured and dimensioned in such a manner that, when the orthosis is placed onto a hand, said main section at least partially surrounds the forearm and surrounds the carpal bone region and extends here from a forearm-side end facing the elbow joint over the wrist itself and the carpal bones as far as the metacarpal bones of the fingers. In order to accommodate the thumb, the thumb section extends from the main section to the side and is arranged and dimensioned in such a manner that, when put on, said thumb section surrounds the metacarpal bone of the thumb and extends at least along part of the proximal phalanx of the thumb beyond the metacarpophalangeal joint. Stabilizing bars are incorporated in the region of the thumb section, said stabilizing bars, when put on, extending laterally in the longitudinal direction of the thumb and being secured by the main section and the thumb section.
Orthoses of this design can indeed in principle provide a good immobilizing action. However, in practice, the immobilization actually achieved is insufficient. The lateral splinting for the thumb still permits a high degree of residual mobility. Nevertheless, the orthoses always restrict the mobility of the wrist. In addition, they frequently have large amounts of textile portions which are associated with the problems of rapid soiling and resultingly required cleaning, during which the patient cannot use the orthosis. By contrast, in the case of the known orthoses, the use of plastics conceals a high potential for pressure points. In addition, they are frequently difficult to put on, in particular taking into consideration the fact that the user has only one hand available.